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Sound card DAC tutorial

James_Lehman

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Oct 31, 2008
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Instead of just using only the 8 "positive" bits of the dac, why not offset the dac to be centered at 2.5v and take advantage of the full 16bits?

The one thing that you want to be absolutely sure of is that when there is no wave data, you get zero volts from all of the channels!

That puts your galvo mirrors in the center of their rotation and blanks all your lasers.

Zero volts out of a DAC channel is just as much of a signal as anything you get while playing a wave!

When you're not playing a wave or streaming audio data in some way, you are in effect playing a stream of binary zeros!

Binary zero MUST produce zero volts on the other side of the DAC!

As soon as the device driver is installed and running, the DAC is engaged and in total control of your projector until you interrupt that connection.
 
Last edited:



Kalmito

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Jan 4, 2012
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Hi guys!

I made this offset, but its not working.
I connected offset to usb sound card , i make to X and to Y 0V and i connected to galvos AL30K "PT30K" but nothing. I connected to sound card speakers it makes sound if I click to projector on, but galvos dont work. I set sound card to 6channel.
I use LaserRoom Software and LFI_Player_V1.1.6

What is wrong !?
Please Help!

Sorry for bad English!
 

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fenyvesi

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Jun 30, 2014
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It is suspicious for me in picture 5 that the connections should have been soldered on the other side of the capacitors (coming from the IC).
George Fenyvesi
 




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